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Weird 'burning insect' smell through vents when car comes to a stop.... BMW 330ci 2002, 103000 miles.

4.1K views 12 replies 4 participants last post by  Furiousbullet  
#1 · (Edited)
Hello all,

Over the last few days I have noticed a really bad smell coming through the vents of my BMW when I come to a stop. It will then linger and dissipate as I drive. I am pretty sure its not burning oil, it smells like a burning insect, only way I can describe it.

My front left brake causes break vibrations since I have owned it so I am thinking it could of possibly become stuck, but I will check that tomorrow by doing the temperature test. My other theory is the VCG needs replacing, only that would cause a burning oil smell right? Could someone remind em what a burning smell is like if compared to something please? really can't remember haha. Unless the VCG is so knackered it is that itself causing the smell. I need to do some futher inspections tomorrow in day light but I have looked into the air filter housing and there was nothing.I do need to check the cabin filter tomorrow.

Basically just wanted to post this up to one confirm what an oil smell is like? like a burning insect?
and 2 to see what you guys reckon as you were very helpful last time I posted :)

Any advice would be appreciated!

Many thanks,
Sam.
 
#3 ·
what above sez its a very common fault your prolly smelling burning oil dripping on the manifold sporadically....

pretty sure i posted a good how to renew the gasket on here somewhere...ive done the job on 2x 330's its easily do-able if done right and ya take ya time...

but if ya sure its not oil i dunno....
 
#4 ·
Ok thanks guys, will look into it more tomorrow, hopefully it is the gasket cover because that looks pretty easy to do! This sounds silly, but can anyone describe to me what burning oil smells like I'm words or something which is similar smell to it? I think half of my problem is I have forgot what it smells like!
I said a burning insect smell, in other words a really strong burning paper smell which is more bitter...
 
#5 ·
Hard to say, I'm not sure what burning insects smells like either...
It is pretty subjective, I can tell the different in smell between burning oil, burning coolant, evaporating coolant, and even between common rail and older injection pump diesels (common rail is more acrid from NOx)

If you have enough old cars, you learn to recognise the smell of repairs!

Your description to me sounds more like burning plastics, but leaking oil is very common, and most likely the issue.
Feel for damp where the engine leans over above the exhaust and you should see weeping oil.
 
#6 ·
Hey guys, quick update, I did a full inspection this morning on the issue. My front left break is constantly rubbing on the disc brake causing the smell I was trying to explain. The brakes have had a hard rumble from the same side under heavy braking since I brought the car (2 months ago) so I guess the callipers have finally stuck. The car is now in the garage having this sorted out hopefully the disc isn't warped as well.
I checked the VCG as well, I looked through the service history from the previous owner and a valve cover kit was brought a year ago. I felt the outside of the seals and they do feel rubbery suggesting this has been done. However, every now and again white smoke did keep appearing from the rear left (looking from front of car) behind the engine near where the exhaust manifold is suggesting there is oil leaking somewhere. My question to you guys is, is it possible for someone to do a cr*p job on a VCG change? because there is also oil running from some other areas but not sure if this was from before the last owner changed it. Is it possible someone has incorrectly put the new seal on and it has just failed again, or is this unlikely? Or should I be looking into something else other than the VCG?

Thanks guys you have been of great help so far!
 
#8 ·
So your saying it is very possible to do it wrong. I think I will just have to do it again properly, ensuring the areas which should be spray sealed are sealed. If that doesn't work move onto the next job but hopefully that does sort it out. I did ask the garage to look into it aswell so maybe they can tell me if it is definately leaking tommorrow. :)
 
#13 ·
UPDATE - Car back from garage today. Brake pads did get re-done, however this wasn't the cause of the smell. It isnt the rocker gasket either, they said it is clean as a whistle behind the engine.
I took the main guy at the garage with 25 years of bmw experience for a spin afterwards just to make sure he was smelling what I was and he said its my heating system, loads of bacteria in it. He said generally just leave the AC on because it is alot cleaner and sure enough the smell doesn't come in when I do that. He said don't feel like an iodiot because it does smell like something burning, I have had it before.
I can still smell the smell coming from the driverside corner of the bonnet near the windsheild when I get out of the car however which concerns me a little. He recommended to leave engine running with heater on full temp to burn it off but he said he is pretty sure thats what it is, I felt like an idiot!

Does this sound right to everyone else? Does anyone know where all the heating components are found under the bonnet? I asked about the AC pollen filter and he said its no that, its probably more to do with the pipes and I presume another filter possibly located elsewhere? I do trust this garage, they are very good and BMW specialists I just wanted to get other peoples opinions aswell....

Thanks guys